In [1]}, it is shown that, for \(E_{\mathrm {cm}}\ge 0\) , \(I_{\mathrm {cm}}\)  is concave upwards as a function of Newtonian time, and its time derivative (essentially, the dilatational momentum, \(D\) ) is monotonic. This implies that \(I_{\mathrm {cm}}\)  is U-shaped, with a unique minimum at \(D=0\)  that divides all solutions in half. This is the so-called Janus Point.This designation was first put forward in [2]}. Interestingly enough, the complexity function (REF ) has a minimum near this point and grows in either direction away from it, whereby automatically defining a time-asymmetric dynamics for internal observers, i.e., ones within one of the two branches at either side of the Janus Point.
